For the production of a belt-like woven cloth in the prior art, while using a twist yarn as a warp, such as a safety belt or a sling, there is a method in which a beam is prepared by winding thereon a predetermined number of twist yarns before a weaving operation, or a method in which a bobbin is formed by winding thereon a preliminarily prepared twist yarn and a plurality of the bobbins are arranged on a creel to be supplied to a loom as warps.
There are problems when a twist yarn is used for a weaving operation as a warp yarn. That is, it is necessary to vary a twist number in accordance with the use of a woven cloth and/or specific properties of the yarn so that the required feeling to the touch is obtained in the resultant cloth. Since a yarn twisting is not usually carried out by a weaver but is done by an outside twister, it is almost impossible to change a twist number after the yarn twisting has been completed, even if it has been found that the twist number is unsuitable for the desired cloth. Also, since it is not certain that the same length of twist yarn is wound on the respective bobbin, a waste of the twist yarn may be generated due to this difference of the yarn length between the bobbins.
Moreover, since a length of the twist yarn wound on a bobbin is at most one half, usually less than one third of that of a large packaged material yarn bobbin, a troublesome bobbin exchanging and yarn tying operation is necessary midway in the weaving process, and, in some uses, the resultant product may be inferior in the tied portion and cannot be used. As stated above, when a cloth is woven while a twist yarn is used as a warp yarn, there are more inconveniences compared with a case when non-twist yarns are directly supplied to a loom from a creel.
On the other hand, when a non-twist yarn is used as a warp yarn and is directly supplied from a creel, it is almost unnecessary to tie original yarns to each other during the weaving process, because the yarns are supplied from the respective large packaged bobbins. Further since an unwinding process and a warping process can be eliminated and a yarn twisting through an outside twister is unnecessary, the productivity thereof is superior to that of the former. However, there are several problems in the product quality in that the feeling to the touch is limited to a narrow range, resiliency is poor and durability against abrasion is inferior. In addition, there are also problems in the weaving process in that many fluffs occur in the warps due to filament breakages in non-twisted yarns, because of which in an extreme case the loom must be stopped and returned to a normal state.
To solve the above problems, the present inventors proposed in Japanese Patent Application No. 57-029084 a creel in which a plurality of bobbins are arranged, each carrying a non-twist yarn thereon and provided with a twisting device similar to a flyer mechanism, and the non-twist yarn is delivered from the bobbin and simultaneously twisted thereby. According to this creel, the non-twist yarn in a large packaged bobbin can be supplied to a loom while being twisted but there is a serious problem in that the installation cost is expensive.
To obtain effects similar to the above apparatus at a relatively lower installation cost, in Japanese Patent Application No. 60-189847, a creel was proposed using a ring/traveller type twisting mechanism. Thereby, the structure became more simple and the installation cost was reduced relative to the former structure. Accordingly, various inconveniences could be solved, which occur when the weaving operation is carried out by using the twisted yarn. However, this was not a perfect solution to the problems inherent in the prior art because the installation cost is not drastically reduced compared with a cost for the yarn twisting process.
In addition, in the above two prior art, a spindle driving means constituting a main part of the twisting mechanism is described as a combination of shaft and bevel gears, which is so complicated in structure that a reduction in the installation cost is prevented.
In Japanese Patent Application No. 60-189847, an apparatus is disclosed, which supplies twist yarns having S twist and Z twist, respectively. In this apparatus, although a rotational direction of the spindle can be changed by varying a belt wrapping arrangement while using a single motor, or by using two driving systems, it is not clear that the rotational speed, that is, the twist number is variable.
Further, in the above two documents, while there is only a disclosure in that a material yarn formed on a straight paper tube (cylindrical paper tube) is used, there is no disclosure regarding the use of a tapered paper tube or an aluminum pirn, from which a yarn is withdrawn in one direction.
If twist yarns are supplied to a loom for weaving a cloth of a simple design, the abovesaid prior art can be satisfactorily applied.
However, in a complicated cloth in which yarns of various kinds and/or of thickness are mixed, it is necessary to use an apparatus which can change not only a rotational direction but also a rotational speed (twist number) of a yarn to be treated. Moreover, a creel is desired which can be also used for bobbins other than a straight paper tube.
It is a primary object of the present invention to provide a method for directly supplying twist yarns from a creel to a loom, which can stand comparison with the prior art in which non-twist yarn is supplied directly from a creel to a loom. It is a secondary object of the present invention to provide an improved creel in which a twist number and a twist direction of the supplied yarn can be changed if necessary and which has advantages in that the selection range of bobbin shape on which a non-twist yarn to be treated is wound can be widened to a great extent, the use thereof can be extended, and drastic reduction in the installation cost is possible.